CaesarCipher.java

class caesarCipher {
public static String encode(String enc, int offset) {
offset = offset % 26 + 26;
StringBuilder encoded = new StringBuilder();
for (char i : enc.toCharArray()) {
if (Character.isLetter(i)) {
if (Character.isUpperCase(i)) {
encoded.append((char) ('A' + (i - 'A' + offset) % 26));
} else {
encoded.append((char) ('a' + (i - 'a' + offset) % 26));
}
} else {
encoded.append(i);
}
}
return encoded.toString();
}
public static String decode(String enc, int offset) {
return encode(enc, 26 - offset);
}
public static void main(String[] args) throws java.lang.Exception {
String msg = "Anna University";
System.out.println("Simulating Caesar Cipher\n-----------------------");
System.out.println("Input : " + msg);
System.out.printf("Encrypted Message : ");
System.out.println(caesarCipher.encode(msg, 3));
System.out.printf("Decrypted Message : ");
System.out.println(caesarCipher.decode(caesarCipher.encode(msg, 3), 3));
}
}
OUTPUT:
Simulating Caesar Cipher
Input : Anna University
Encrypted Message : Dqqd Xqlyhuvlwb
Decrypted Message : Anna University